1. Field of the Invention
The invention concerns a process for the treatment of the combustible portion of crushed domestic waste with dense-medium material being removed and being dried to a residual moisture of 8 to 10% before entering a briquetting press. The domestic waste is frayed in its dry condition after fine inert material has been sifted out.
2. Description of the Prior Art
In a known process household garbage is crushed in a hammer mill and is dried in a suspended drier while the dense-medium material is removed, and the combustible fraction separated in this way is supplied to a briquetting press without any subsequent treatment. The bonding of the particles during the briquetting is effected to a smaller extent by the fibrous edges of cellulose-rich particles, such as pieces of paper, which develop during crushing in the hammer mill but to a larger extent by the flying fine inert particles passing in a considerable amount in an upward direction through the suspended drier. The fine inert particles have greater bonding power because the fibrous edges of the cellulose-rich particles produced in the moist original condition of the garbage are so soft that they are mechanically blunted when transported to the suspended drier and in the drier itself such that the edges become mostly smooth. The briquets produced in this way have only a moderate heating value owing to the fine inert portion.
The property of fine inert particles to act as a bonding agent is still more distinct in another known process (German Pat. No. 25 10 465) in which, after a coarse crushing of the household garbage, the entire inert portion remains in the transported substance during its passage through a disintegrator and is dried together with the treated material. There exists no separated combustible fraction. Consequently, the briquets which are produced without an additional mixed-in bonding agent have such a low heating value that they are practically unsuitable to be burned but are intended to be gasified in a gas generator. This process has no relation to the present invention.